Active cannulas

ABSTRACT

An active cannula which does more than merely maintain a passage is usable to create and/or enlarge a passage, to position a scope or instrument, to move or locate tissue, etc. The cannula can vary in size or shape as needed, intraoperatively. Because a cannula of the present invention is expandable, the surgeon can make a relatively small incision, stretch the tissue with the expandable cannula, contract the cannula and remove it, allowing the skin to come back to its unstretched condition. Thus, a smaller incision can be made to fit the same size instrument. The cannulas can assume such a non-circular shape, to fit into a natural skin opening and cause less trauma. The devices can be used to seal off a space, expand an existing space or a potential space for working or visualization, move tissue (for example, to stretch an incision), or protect tissue.

RELATED APPLICATIONS

[0001] This application is a continuation of co-pending U.S. applicationSer. No. 08/727,968, which is a divisional of U.S. application Ser. No.08/462,420, filed on Jun. 5, 1995, now U.S. Pat. No. 6,171,299, which isa divisional of U.S. application Ser. No. 08/195,337, filed on Feb. 14,1994, now U.S. Pat. No. 5,514,153, which is a continuation-in-part ofU.S. application Ser. No. 07/792,730, filed on Nov. 15, 1991, now U.S.Pat. No. 5,295,994, and a continuation-in-part of U.S. application08/054,416, filed on Apr. 28, 1993, now abandoned, which is a divisionalof U.S. Ser. No. 07/487,645 filed on Mar. 2, 1990, now U.S. Pat. No.5,331,975. The benefit of the earlier filing date of aforementionedapplications is hereby claimed. The specifications of the aforementionedapplications are hereby fully and expressly incorporated by referenceherein.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to medical devices, andparticularly to expandable medical devices such as cannulas, catheters,retractors, and similar devices.

[0003] Existing cannulas and/or retractors as used in endoscopic surgerytoday are passive devices which are fixed in length and width. Theycannot be varied intraoperatively in length and width to accommodatelarger devices or varying size devices through the skin.

[0004] Skin and subcutaneous (subsurface) tissues are viscoelastic: theywill gradually stretch without tearing. Once the tissue is slowlystretched it maintains its expanded condition for a period of time.Alternatively, the tissue can be stretched further, for example toprogressively stretch out an incision. Then, after relaxation, thetissue will regain its original unstretched condition without havingbeen damaged.

[0005] Current methods used for retracting tissue and improvingvisualization are mechanical separation using metal refractors duringopen surgery, or the direct pressure of an unconfined flow of fluid suchas water or CO₂ during fiberoptic surgery. A typical mechanical externalfixator has pins driven through the bones and mechanically distracts theelements of the joint. Problems with the water method include fluidextravasation including into and through the tissue itself. Increasedpressure and swelling result in the area, resulting in edematous orswollen tissue. Excess pressure from mechanical refractors may causenecrosis or tissue death. With these methods, it is impossible tomonitor the pressure being applied to the body tissues, and tissuedamage or necrosis can result.

[0006] While operating from within the body, i.e., fiber optic assistedsurgery as opposed to open surgery, there is no known way to selectivelymove or retract tissue, either hard tissue such as bone or soft tissue,out of the way to improve visualization. No device in use adequatelyallows a surgeon to create an actual space or expand a potential spacein the body, by separating adjacent layers of tissue. The prior art doesnot disclose a retractor which is powerful enough and made of a materialwhich is strong and resilient enough to, for example, separate tissueplanes from within. Such a device, especially in the field of fiberoptic surgery, would allow a surgeon to visualize and operate withoutusing the conventional bulky and awkward mechanical Detractors whichrequire large open incisions. Such a device would also permit workingwithin the body without damaging a great deal of tissue in the pathbetween the skin opening and the working area, by minimizing theexternal orifice or skin incision.

SUMMARY OF THE INVENTION

[0007] The present invention is a system of refractors and/or cannulaswith which a surgeon can use to take potential spaces within the bodyand turn them into existing spaces safely and easily and controllably inorder to safely visualize appropriate tissue and operate. The cannulaand/or retractor selectively moves appropriate tissue out of the way toenable a surgeon to see and work better within the body, and selectivelymoves body parts such as joint parts or soft tissue planes in order tocreate a space between the tissues for visualization and for working.

[0008] A cannula and/or retractor of the present invention may have afluid-operated portion such as a balloon or bladder to retract tissue,not merely to work in or dilate an existing opening as for example anangioscope does. The fluid-filled portion is flexible, and thus thereare no sharp edges which might injure tissue being moved by theretractor. The soft material of the fluid-filled portion, to an extentdesired, conforms to the tissue confines, and the exact pressure can bemonitored so as not to damage tissue. The expanding portion is lessbulky and more compact, and the pressure it applies at the tissue edgescan stop bleeding of cut tissue. These are all features not possessed bya conventional mechanical retractor.

[0009] With a typical mechanical retractor, the opening in the skin andthence inwardly must be larger than the surgical area being worked upon,in order to be able to get the mechanical retractor into position. Thesurgeon must damage a large amount of tissue which may be healthy, inorder to expose the tissue to be worked on. The cannula and/or retractorof the present invention minimizes damage to tissue in the way of thetissue the surgeon needs to expose, which was previously cut in a largeopen exposure. With the cannula and/or retractor of the presentinvention, the opening at the skin is smaller at the skin where thedevice is inserted, and wider at the location inside the body where thecannula and/or retractor is expanded. The cannula and/or retractor isfirst placed into the body in an unexpanded condition, and then, as itis expanded, pushes tissue out of the way in deeper layers of the bodyone can see and safely operate on affected tissue. Thus, less undesiredtissue damage occurs.

[0010] The bladder is pressurized with air or with water or anotherfluid. The fluid used in the bladder must be safe if it accidentallyescapes into the body. Thus, besides air, such other fluids as dextrosewater, normal saline, CO₂ and N₂ are safe. The pressure in the bladderis monitored and regulated to keep the force exerted by the retractor ata safe level for tissue to prevent tissue necrosis. The retractor canexert a pressure on the tissues of as high as the mean diastolicpressure of 100 mm of mercury, or higher for shorter periods of time,while still being safely controlled. Typical inflatable devices such asangioscopes do not have anywhere near the strength, or the ability tohold enough fluid pressure, or shapes to retract tissue as describedherein. As compared to prior art devices, the retractor of the presentinvention operates with greater pressure within the bladder, since it ismade of stronger materials such as Kevlar or Mylar which may bereinforced with stainless steel, nylon, or other fiber to preventpuncturing and to provide structural shape and support as desired. Suchmaterials are strong enough to hold the necessary fluid pressure ofabout several pounds or up to about 500 mg Hg or more and exert theneeded force on the tissue to be moved. The choice of material is wellwithin the ability of one familiar with such materials and accordinglywill not be gone into in further detail herein. The present retractor isthus able to exert substantially more force on adjoining tissues than aprior art device. The shapes of the refractors are specific for eachapplication, and may include separate variable chambers which aresequentially controllable, to control the direction of tissueretraction.

[0011] Surgeons operate along tissue planes. Once a surgeon finds atissue plane, he dissects along it, starting the separation process withthe knife. The cannula and/or retractor holds the tissue layers apartand helps and eases in defining and further separating the tissue layersas the surgeon operates along the tissue planes, helping to spread anddefine the planes. The cannula and/or retractor helps to separate thetissue layers, increasing the space for operating, and improving thesurgeon's ability to separate and visualize, leading to better and safersurgical technique.

[0012] A preferred use for the present retractor is in the field offiber optic surgery, including endoscopy, arthroscopy, laparoscopy, etc.which require looking into and operating within a limited space with afiber optic light and camera. The bladder expands into an area of softtissue—for example the bursa—and pushes it out of the way. The bladdercan be left in place during the operation, or it can be deflated andremoved, and the arthroscope and other instruments can be put into thespace created.

[0013] The bladder may be a bellows type device in which the materialdoes not stretch but which expands when pressurized from within andwhich is collapsed by the use of suction. In this case, it wouldpreferably be made of a polymer of the class including Kevlar or Mylarfabric for strength and structural integrity. The bladder may generallyalso be made from any very thin walled polymer.

[0014] The bladder may also be made from a biocompatible and/orbiodegradable material, so that if it can not be removed from the bodyfor some reason, or if the surgeon desires to keep the bladder in placein the body for a period of time, it will not damage the tissue and mayeventually be reabsorbed into the body. Such a biodegradable bladder maybe left under the skin postoperatively to stop postoperative bleeding orto keep tissue expanded. Alternatively, the bladder may be made of astretchable material which stretches when pressurized from within, andthen collapses partially of its own accord when depressurized or alsowith the help of suction. The retractor may be transparent for bettervisibility, but it need not be for some applications. Also, theretractor can be disposable. The material choice is within the skill ofthe art. One surface of the bladder may be made of or have thereon areflective surface to reflect light to see around a corner.

[0015] A most typical construction for the cannula and/or retractor ofthe present invention is an inflatable bladder situated on the end of ashaft, which may be flexible or rigid,-which is pushed through an extraopening in a scope or cannula or through a separate portal, and whichexpands at the end of the shaft.

[0016] The retractor can be located on a scope, either on the endthereof or movable axially through a channel along the length of thescope. The retractor can alternatively be mounted on a cannula. Theretractor can be mounted on a separate shaft passing through an existingchannel in a cannula; it can be inserted through a separate hole in thecannula or the scope; or it can be inserted through a separate openingin the body. The shaft with a retractor on the end can be pushed or slidthrough the cannula,, side by side with a scope. Alternatively, thebladder can expand out of, then recess back into, a groove on a cannulaor scope. The retractor can be used to create a space right by thescope, or possibly at a location spaced from the end of the scope.

[0017] The bladder itself can be round, eccentric, oval, conical,wedge-shaped, U-shaped, curved, angled, or it may be in any shapedesirable to optimize the particular application. The bladder may beirregularly shaped when inflated, that is, it may expand to a greaterradius in the area where it is desired to look (where greater exposurespace is needed).

[0018] Vacuum can be used to deflate the bladder. The bladder may thenbe removed by sliding it out the portal directly.

[0019] The present invention is described herein as relating to cannulasand/or refractors. A cannula is a device for insertion into or throughbody tissue to provide a working passage for surgical instruments,scopes, etc., as in endoscopic or arthroscopic surgery. A catheter, onthe other hand, is an artificial fluid passage primarily used forinsertion through an existing body opening. The two types of deviceshave very different structures and structural requirements. For example,a catheter is usually flexible, very small in diameter, and not suitablefor maintaining a working passage through normally closed body tissues,while a cannula is more rigid, larger in size, and designed specificallyto provide a working passage for surgical instruments and scopes throughnormally closed body tissues. It should be understood, however, thatmany of the features of the present invention can with suitablemodifications be applied to the catheter art. Accordingly, the presentinvention is not limited to cannulas per se, but may be applicable tocatheters or other devices also.

[0020] The present invention defines an active cannula or sleeve whichdoes more than merely maintain a channel or passage. It is an activedevice usable to enlarge a channel or passage, to position a scope orinstrument, to move or locate tissue, etc. The cannula can vary in sizeor shape as needed, intraoperatively. Typically, with a passive(non-expandable) cannula, a surgeon must make an incision in the skinand muscle large enough to receive the largest instrument to be passedthrough the incision to the surgical area. Because a cannula of thepresent invention is expandable, the surgeon can make a small relativelysmall incision, stretch the tissue with the expandable cannula, contractthe cannula and remove it, allowing the skin to come back to itsunstretched condition. Thus, a smaller incision can be made to fit thesame size instrument. This results in less trauma and scarring and aneasier operation.

[0021] Further, known cannulas are generally round, while skin expands(from an incision) in an elliptical fashion, between tissue planes.Thus, the present invention provides cannulas which are or can assumesuch a noncircular shape, to fit into the natural opening and cause lesstrauma.

[0022] The devices of the present invention are usable in endoscopicprocedures generally. The devices can be used to seal off a space; toexpand an existing space or a potential space for working orvisualization; to move tissue (for example, to stretch an incision) orto protect it. Other uses within the skill of the art but not enumeratedherein are within the scope of the invention.

[0023] The cannulas of the present invention allow for the progressivestretching of an incision in skin or subsurface tissue in order to allowimproved exposure, while minimizing damage to the tissue by making theactual incision as small as possible.

[0024] In the arthroscopic model, a fixed cannula is placed through theskin to the subsurface tissues into a joint. Different size workingdevices (shavers, burrs, scissors, punches, scope, etc.) are placedthrough the cannula to visualize or to work in the subsurface area atthe distal end of the cannula. The cannula can be progressively expandedor stretched radially outwardly, to stretch or expand the skin andsubsurface tissues. The cannula typically expands along its entirelength, although it may in some cases be expandable at selected portionsalong its length.

[0025] The expansion can be in a circular pattern, or it can be in anoval or elliptical or other pattern to accommodate (a) the tissue planesor (b) the instruments being inserted through the cannula.

[0026] The cannula can expand inwardly to act like a valve or a seal. Orit can expand both inward and outward.

[0027] The cannula is preferably flexible—that is, it is bendable aboutan axis extending perpendicular to the longitudinal extent of thecannula. In other words, the cannula as a long straight object is notrigid but can bend so that it is not straight. This allows the cannulato conform to the body tissues to the extent desired.

[0028] All cannula bodies can be multi-lumen for passages through whichextend structure for control of bladders, tools, scope, etc.

[0029] In a first embodiment, a cannula may be of a stretchable material(such as a polymer) which is introduced into the body with a trocar. Thetrocar is then removed. Progressively larger dilating devices are placedinside the stretchable cannula, as needed, to progressively stretch outthe skin and tissue to a larger size in order to introduce largerinstruments through the cannula. Each time the cannula is enlarged, thestretched tissue-remains in its stretched condition for a period of timebecause of its viscoelastic properties.

[0030] One way of stretching the cannula is by placing inside thestretchable cannula a bladder (round or elongated in the shape of asausage, for example) which can be inflated to uniformly stretch thecannula and tissue. The bladder can be deflated and removed, leaving theenlarged opening.

[0031] In a second embodiment, the cannula is itself inflatable forexpansion. The cannula is basically an inflatable cylinder withexpansions in both the inner diameter and the outer diameter. Asinflated, the device expands to a preformed shape with the innerdiameter following the outer diameter and expanding outward to create aprogressively larger opening. Filaments or cords can be-placed betweenthe inner and outer walls to limit their separation from each other. Theinner wall can be more rigid.

[0032] In a third embodiment, the cannula includes one or morestretchable (inflatable or expandable) parts and one or morenon-stretchable parts. The non-stretchable parts can be metal or plasticpieces such as curved plates, joined by the stretchable elements whichextend longitudinally between them. These stretchable elements can bebladders. As larger devices are passed through the cannula, thestretchable portions expand and the plates move outwardly to stretchan-appropriate opening.

[0033] In any of these cases, one can monitor and control the amount ofpressure being applied to the tissue upon expansion of the cannula, soas to not exceed a certain critical pressure and damage tissue. This canbe done by monitoring the actual size of expansion, the amount of air orfluid introduced to inflate the device, the fluid pressure within thedevice, etc.

[0034] There are numerous possibilities of a cannula-with-bladder or(catheter-with-bladder) construct.

[0035] One specific example is an arthritis irrigation system. This is amulti-lumen tube which has one lumen/portal for inflow of irrigationfluid and a second portal for suction (return). The tube is flexible andhas its distal end placed in a joint to be irrigated. The tube is fixedin place by an expanding device as discussed below. Fluid flowingthrough the joint flushes out debris in the joint. The device caninclude third or additional lumens for a scope or tools to pass through.Since the tube is both flexible and fixed in place, it can remain in thepatient even when the patient is ambulatory. It thus provides apermanent passage for the surgeon to access the joint.

[0036] There can be multiple bladders at a location on the cannula,independently controlled, to position the cannula. At least one bladderis preferably at the tip of the device to expand or stretch tissue or tostabilize the device.

[0037] In any of the illustrated embodiments, the bladder can be made ofa different material from the cannula, as opposed to, for example, aFogarty catheter which is made of all one material. This will allow forvariations in construction, with the bladder being made of one materialto better perform its functions and the cannula or other supportingmember being made of another material to better perform its functions.

[0038] The expanding (inflatable) bladders of the present invention areconstructed in various manners as set forth below. The bladder canstretch cannula walls. The bladder can move tissue and allow selectivemanipulation of tissue, even arthroscopically. The bladder also has atamponade effect, lessening bleeding in the surrounding tissues.

[0039] The bladder also distributes the refractive force, reducingstress on delicate tissues such as nerve tissue.

[0040] There can be one or more bladders at any given location or on anygiven instrument. Multiple bladders can be controlled as independentstructures or as one unit. Specific structure and control is based onthe particular application.

[0041] The surface of the material can be pebbled or roughened orridged, or have serrated edges, to better grip tissue and hold theretractor in position. Of course, the surface must still remain smoothenough so that the retractor is easily removable without damage to thetissue it contacts.

[0042] The bladders can expand by well in excess of 200%.

[0043] The bladder is preferably made of an elastomeric material whichis strong-enough to move tissue as desired. A suitable material for theexpandable bladder is Silastic® elastomer, which is available from DowCorning in medical grades. Other suitable materials are silicone, orlatex, or PVC.

[0044] The bladder may be made of a non-elastomeric material which isstrong enough to move tissue as desired. A suitable material is Mylar®fabric. A non-elastomeric material may have a more controllable shapebecause it will not stretch. A non-elastomeric material will collapseinward automatically due to the pressure of the tissue around it,whenever it is not inflated. Many of the illustrated embodiments whichare discussed as being made of an elastomeric material can also be madeof a nonelastomeric material.

[0045] The expandable bladder can be made of a biodegradable material.In such a case, the biodegradable portion can be made detachable fromthe remainder of the retractor, so that it can be detached and left inthe body after surgery. This is useful, for example, to prevent adjacenttissue planes from scarring together after surgery. The biodegradablemass will in time disappear, allowing the tissues to adjoin after theyare healed.

[0046] The bladder can be made of a composite material—that is, aparticle or fiber-reinforced material. Many suitable materials are inuse in industry. Composite materials can be made stronger while stillretaining flexibility and fluid-sealing capabilities. Compositematerials also provide the capability to have a bladder assume aspecific shape upon expansion.

[0047] The bladder can be made of a composite biodegradable material.

[0048] The bladder(s) can be made of two different materials bondedtogether, such as a stretchable (low-modulus) and a non-stretchable(high-modulus) material. Mylar® and Silastic® are suitable materials, ormetal for a stiff material. As the inflation fluid (typically air) isintroduced, it takes the path of least resistance-and thenon-stretchable material fills out to its expanded shape first. Then thestretchable material expands, in a manner constrained by thealready-expanded non-stretchable material.

[0049] The bladder can be made of a transparent material to provide abetter view of the operating area and improved visualization.

[0050] The bladder may have a dual durometer layered construction, witha thin layer for fluid retention overlying a thicker layer for shaping.Other laminated constructions are possible, also.

[0051] The external shape of-the retractor when expanded, and the amountof expansion, are designed for the specific application on which thatretractor is to be used. For example, if the surgeon is working againstbone, he can select a retractor which is configured so that it staysflat against the bone, and expands away in the opposite direction, topush tissue away from the bone and create a working and visualizationspace next to the surface of the bone.

[0052] There are several ways to control shape of expansion-thick andthin areas (gaps, ridges, stiffened areas, etc.), fiber reinforcing,dual durometer construction, different materials affixed together,tethering cords, and pre-shaping.

[0053] Upon application of a given amount of force, a thinner materialwill stretch more than a thicker material. Thus, all other factors beingequal, an inflatable device will stretch more where it is thinner, andwill stretch less where it is thicker. This occurrence can be used tocontrol the shape into which a bladder expands when it is inflated byfluid under pressure.

[0054] As a simple example, it can readily be seen that if a bladder hasone half made of a very thick material and one half made of the samematerial but much thinner, then upon the introduction of fluid underpressure, the thin material will stretch more quickly (easily), and thebladder will expand unevenly. The thin half of the bladder will deformmore under the same pressure until the force needed to stretch itfurther is equal to the force needed to stretch the thicker material.The half made of the thicker material will then begin to stretch, also.Thus, the thickest point on the wall will be at the crown area (farthestout).

[0055] The areas of variation in cross section can be of various shapesand directions to control the expansion rates. For example, thecircumference of a bladder can be configured as an incomplete hoop.Thus, most of the circumference is of a thicker material, while selectedareas are thinner. Upon the introduction of fluid under pressure, thethinner areas will expand first, with each thicker area moving outwardlyas a whole.

[0056] There can be ribs around the circumference. Areas of thickness orthinness can extend longitudinally, circumferentially, radially, or inbroken segments.

[0057] A second way to control the shape of expansion is the use of afiber reinforced (composite) material. The direction of the fibers,along with their number, spacing, layering, and length, controls therate of expansion of the matrix material. Also, areas devoid of fiberswill expand faster or further than areas with more or stiffer fibers.

[0058] Specifically, the fibers resist stretching along their length.Thus, the bladder will stretch more in a direction across the fibers, orwhere the fibers are not present, than in a direction along the fibers.Fibers can be placed at the edge of the bladder to maintain the shape ofthe bladder when inflated. Fibers can be layered, with one layer in onedirection and another layer in another direction to control expansion inthe other direction. Fibers can be placed in overlapping layers, toallow expansion in one plane only.

[0059] Adding fibers makes the bladder more puncture and tear resistant.Note that the bladder can, for this purpose, also be made of or includea self-sealing material.

[0060] A third way of controlling expansion shape is to preshape thebladder to assume a certain form when expanded. This is done in themolding process. The bladder is typically formed on a mandrel which isof a particular shape and which is sized about half way between theunexpanded and the expanded size of the bladder.

[0061] The pre-determined shape of the unexpanded bladder is basically acombination of varying wall thickness and ribbing, made on a three partmold.

[0062] In certain experimental models constructed to date, the bladderis bonded onto a nylon stalk of 7 mm O.D. The bladder is stretched fromabout 3 mm to about 7 mm at its smallest dimension. This pre-stretchedarea puts the material under tension. Any larger diameter portions arerelaxed. As the bladder is expanded, the smaller diameter portion, whichis already partially expanded, stretches at a limited rate. The largerdiameter portion (under no load) expands at a faster rate. They balanceout at a point where all the material is under basically the same loadin tension. This is the point at which the shape is attained.

[0063] It should be understood that this particular example and itsdimensions are not limiting, and that any diameter can be used. This isan example of a specific sized cannula for a specific application.

[0064] With a typical material (silicone), the more you stretch thematerial, the more force is needed to stretch it further.

[0065] The prestretching of the bladder is done so that the bladder liesflat on the cannula body. The bonding areas are such that as theexpansion takes place the material expands radially outwardly as well asaxially.

[0066] It can alternately be doubled up at a certain area, such as thetip of a stalk or cannula. This will allow maximum expansion at the tip.

[0067] Tethering cords can be fixed to bladder portions and extendbetween them to control and/or limit the expansion of the bladder. Thiscan be done with bladders made of a composite material or includingplates or other thicker areas. In a cannula construct, the tetheringcords can run between the cannula body to the crown of the bladder tocontrol and/or limit its expansion.

[0068] Plates can be added in which will limit the shape of the bladderor create an edge. For example, if a flat plate is added, the bladdercan expand in a circular fashion but the flat plate will remain flat andprovide a flat area on the outside of the bladder. Or the plate can becircular, or at an angle to create an edge. There can be multiple suchplates added to create specific shapes. Tethering cords can be used toextend to the plate. This can be useful in the cannula construct.

[0069] The bladder can also have a bellows-type construction forincreased expansion control and structural rigidity.

[0070] Suction can be used to collapse any of the devices to facilitateremoval.

BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The foregoing and other features of the present invention willbecome apparent to one skilled in the art upon a consideration of thefollowing description of the invention with reference to theaccompanying drawings, wherein:

[0072]FIG. 1 is a side elevational view of a joint irrigation apparatus;

[0073]FIG. 2 is a longitudinal sectional view through the apparatus ofFIG. 1;

[0074]FIG. 3 is a view taken along line 3-3 of FIG. 1;

[0075]FIG. 4 is a view of an alternate embodiment of the apparatus ofFIG. 1;

[0076]FIG. 5 is a transverse sectional view through an expandingcannula;

[0077]FIG. 6 is a view of the cannula of FIG. 5 in an expandedcondition;

[0078]FIG. 7 illustrates a cannula having an outwardly expanding bladderformed within the wall of the cannula;

[0079]FIG. 8 illustrates a cannula having an inwardly expandable bladderformed in the wall of the cannula; FIG. 9 illustrates a cannula havingan inwardly and outwardly expanding bladder formed within the wall ofthe cannula;

[0080]FIG. 10 illustrates the expansion of a cannula having viscoelasticwalls by means of an inserted inflatable member;

[0081] FIGS. 11-13 illustrate a cannula comprising a cylinder expandablealong its entire length;

[0082]FIG. 14 illustrates an elliptical or an oval-shaped cannula havingtethering cords;

[0083]FIG. 15 illustrates a square-shaped cannula having tetheringcords;

[0084]FIG. 16 is a schematic view of a retractor shown in the unexpandedor contracted and expanded or extended conditions;

[0085]FIG. 17 is a schematic view of a retractor extending through acannula and mounted on the end of a separate shaft;

[0086]FIG. 18 is a schematic view similar to FIG. 17 illustrating theuse of a fiber optic scope with the retractor;

[0087]FIG. 19 is a schematic view showing a retractor inserted through aseparate side opening in a cannula;

[0088]FIG. 20 is a schematic view of a few of the many and variousshapes in which the inflatable portion of the retractor may be formed;

[0089]FIG. 21 is a schematic view of a retractor shown mounted on theend of a cannula and having an opening therein for a scope to passthrough;

[0090]FIG. 22 is a diagram of a fluid supply system for operating aretractor;

[0091]FIG. 23 is a view illustrating the use of a retractor to positionthe end of a scope;

[0092]FIG. 24 is a view similar to FIG. 23 further illustrating the useof a retractor to position the end of a scope;

[0093]FIG. 25 illustrates a cannula having a tethering cord connecting aballoon portion to the cannula wall;

[0094]FIG. 26 is a sectional view illustrating a continuous mass of bodytissue which is free of an opening;

[0095]FIG. 27 is a schematic illustration depicting the manner in whichthe cannula of FIG. 25 is inserted into the mass of body tissue of FIG.26 and expanded to form an open space in the mass of body tissue at alocation adjacent to and axially outward from a distal end of thecannula;

[0096]FIG. 28 is an enlarged view of the cannula of FIG. 27 andillustrating the manner in which a fiberoptic scope and a tool areinserted through-the cannula into the space formed in the body tissue ata location axially outward from the distal end of the cannula byexpanding the cannula;

[0097]FIG. 29 is an enlarged fragmentary sectional view of a cannulahaving a flexible wall and tethers, the flexible wall being shown in aretracted condition;

[0098]FIG. 30 is a fragmentary sectional view, generally similar to FIG.29, illustrating the flexible wall in an extended condition with atether limiting outward movement of a portion of the flexible wall;

[0099]FIG. 31 is a fragmentary sectional distal end view, takengenerally along the line 31-31 of FIG. 30, illustrating the manner inwhich a plurality of tethers extend outwardly from a main section of thecannula toward the flexible wall;

[0100]FIG. 32 is a fragmentary schematic plan view of a portion of aside wall of the flexible wall of the cannula of FIGS. 29-31 andschematically illustrating the relationship between reinforcing fibersin a proximal portion of the side wall;

[0101]FIG. 33 is a fragmentary plan view of another portion of the sidewall of the flexible wall of the cannula of FIGS. 29-31 andschematically illustrating the relationship between reinforcing fibersin a distal portion of the flexible wall;

[0102]FIG. 34 is a plan view of a portion of an end wall of the flexiblewall of FIGS. 29-31 and schematically illustrating the relationshipbetween reinforcing fibers in the end wall;

[0103]FIG. 35 illustrates a cannula which is selectively expandable atone or more selected longitudinal locations;

[0104]FIGS. 36 and 37 illustrate a cannula having a plurality ofcircumferentially spaced expandable segments;

[0105] FIGS. 38-43 illustrate longitudinally extending radiallyexpansible cannula segments;

[0106]FIGS. 44 and 45 illustrate expandable devices having texturedsurfaces;

[0107] FIGS. 46-49 illustrate a cannula having an expandable bladderportion with a varying wall thickness;

[0108] FIGS. 50-52 illustrate flexible bladder portions havingrelatively rigid members molded therein;

[0109]FIGS. 53 and 54 illustrate rigid members molded into theelastomeric material of an inflatable bladder circumscribing a cannulaor other medical device;

[0110]FIGS. 55 and 56 illustrate a cannula having a bladder with adoubled-over bladder portion;

[0111]FIG. 57 is a schematic illustration of a cannula having the samegeneral construction as the cannula of FIGS. 55 and 56, the cannula ofFIG. 57 having tethers and being shown in a retracted condition;

[0112]FIG. 58 is a schematic illustration of the cannula of FIG. 57 inan extended condition with the tethers restraining movement of aflexible wall portion of the cannula;

[0113]FIG. 59 is a schematic illustration of a cannula having the samegeneral construction as the cannula of FIG. 58, the cannula of FIG. 59having a plurality of tethers disposed within a chamber formed by theexpanded flexible wall of the cannula;

[0114]FIG. 60 is an end view, taken generally along the line 60-60 ofFIG. 59, illustrating the manner in which a plurality of tethers areconnected with the flexible wall of the cannula;

[0115]FIG. 61 is a sectional view, taken generally along the line 61-61of FIG. 59, illustrating the manner in which a plurality of tethersextend outwardly from a main section of the cannula toward an inner sidesurface of the flexible wall of the cannula;

[0116]FIG. 62 is a sectional view, taken generally along the line 6-2-62of FIG. 59, illustrating the manner in which a plurality of tethersextend outwardly from a main section of the cannula towards the innerside surface of the flexible wall;

[0117]FIG. 63 illustrates an expanded bladder having adjoining portionswith different material characteristics;

[0118]FIG. 64 illustrates an expanding device having an expandingbladder made of a plurality of materials laminated together;

[0119] FIGS. 65A-65C illustrate triangular-shaped expanding portions;

[0120] FIGS. 66A-66C illustrate trapezoidal-shaped expanding portions;

[0121] FIGS. 67A-67C illustrate the use of overlapping and/or incompletefibers for expansion control;

[0122] FIGS. 68-76 illustrate a variety of bladder devices includingreinforcing fibers and/or tethering cords; and

[0123] FIGS. 77-79 illustrate a structural unit comprising a series ofexpandable bladders laminated together.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0124] FIGS. 1-3 illustrate an arthritis irrigation apparatus 10. Theirrigation system 10 includes a cannula 12 having a disc portion 14 anda longitudinally extending cannula body 16. A central wall 18 dividesthe cannula body 16 into two longitudinally extending lumens 20 and 22.

[0125] An expandable bladder 30 is connected to or formed integrallywith the cannula 12 at the distal end 32 and proximal end 34 of thecannula body 16. The expandable bladder 30 includes a longitudinallyextending wall portion 36 and a transversely extending wall portion 38.The expandable bladder 30 is supplied with fluid under pressure througha fluid supply port 40 closed by a rubber diaphragm seal 42. The lumens20 and 22 are closed by similar diaphragm seals 44 and 46, respectively.The cannula body 16 has a recessed portion 48 in which the bladder 36fits when unexpanded.

[0126] The system 10 is inserted into a pre-made opening until the discportion 14 engages the skin. Upon the introduction of fluid underpressure into the expandable bladder 30, the bladder 30 expands from theunexpanded condition illustrated in FIG. 1 to the expanded conditionillustrated in FIG. 2. The bladder wall 36 moves radially outwardly, andskin or other tissue is trapped between the bladder wall 38 and thedistal surface 49 of the disc portion 14 of the cannula 12.

[0127] The system 10 is thus locked in place, with the distal end 32 inposition in a joint. Appropriate instruments may then be insertedthrough the diaphragm seals 44 and 46 into the lumens 20 and 22,respectively. For example, flushing fluid may be supplied to the jointthrough the lumen 20, while it is removed from the joint by suctionthrough the lumen 22. When the joint is not being flushed, the diaphragmseals 42, 44 and 46 seal the openings in the system 10, and the expandedbladder 30 retains the system 10 in place in the body.

[0128] It should be understood that any number of lumens, other thantwo, can be included in the cannula body 16. The number of lumens islimited only by the size of the instruments to be inserted through thecannula body 16. In a preferred embodiment, the disc portion 14 of thecannula body 12 is about the size of a nickel, with the cannula body 16being correspondingly smaller. Of course, the dimensions and arrangementof the various portions of the system 10 could be modified to enable theplacement of other instruments through the cannula body 16.

[0129] Each of the lumens may have a controllable inflow-outflow portal.These can be substituted for the diaphragm seals. These portals may be asimple tube with an on-off valve attached, as is known in the art, orcan be another suitable structure.

[0130]FIG. 4 illustrates an alternate embodiment of the system 10 inwhich a system 50 includes a round or doughnut-shaped bladder 52extending between the distal end 32 and the proximal end 34 of thecannula wall 16. This doughnut-shaped bladder can be easier or lessexpensive to manufacture, and also can provide more cushioning effect tothe tissues which it engages. Again, tissue is trapped between thebladder 52 and the disc portion 14 of the cannula 12, to retain thesystem 50 in place in the body.

[0131]FIGS. 5 and 6 illustrate a variable size cannula in whichinflatable bladders push apart two relatively rigid portions to movetissue. FIGS. 5 and 6 are transverse cross sections through alongitudinally extending cannula 60, which can be any desired length.The cannula 60 expands radially outwardly along its length.

[0132] The cannula 60 includes a first C-shaped portion 62 having ends64 and 66 and a second C-shaped portion 68 having ends 70 and 72. Aninflatable bladder 74 has one end portion 76 fixed to the end portion 64of the portion 62. The opposite end portion 78 of the bladder 74 isfixed to the end portion 70 of the portion 68. Similarly, a bladder 80has one end portion 82 fixed to the end portion 66 of the portion 62,and its second end portion 84 fixed to the end portion 72 of the portion68.

[0133] The portion 62 has an outwardly facing surface 86 and the portion68 has an outwardly facing surface 88. The cannula 60 has a centralopening 90 which is enlarged in size upon expansion of the bladders 74and 80 to provide a larger working space while reducing tissue damage.Upon the introduction of fluid under pressure into the bladders 74 and80, the portions 62 and 68 are moved away from each other to engagetissue with their surfaces 86 and 88, respectively. The relatively rigidportions 62 and 68 provide increased pushing strength of the cannula 60as compared to a soft inflatable bladder. Further, the cannula 60 alsoholds its structural shape better and is able to maintain the openingbetter. Thus, with the cannula 60, a limited incision can be made in thetissue, which incision is then enlarged by the cannula itself ratherthan with a cutting device. The application of suction to the bladders74 and 80 causes them to deflate to return the cannula 60 to itsunexpanded condition. The tissue is viscoelastic and thus will stretchout during its expansion by the expander 60, and then return to itsoriginal unexpanded shape, i.e., the original size of the incision afterremoval of the cannula. Thus, less tissue damage results.

[0134] Cannulas in accordance with the present invention may have one ormore bladders as part of the cannula wall. These may create inward oroutward expansion. For example, FIGS. 7A and 7B illustrate alongitudinal portion of a cannula 92 having a wall portion 94 defining acentral opening 96 through which surgical instruments or the like can bepassed. The wall portion 94 includes a portion 98 partially defining afluid chamber 100 which may be supplied with fluid under pressurethrough a fluid supply line 102 extending through the cannula wall 94.On the introduction of fluid under pressure into the volume 140, thewall portion 98 of the cannula 92 expands radially outwardly, from theunexpanded condition of FIG. 7B to the expanded condition of FIG. 7A, asa seal or retainer against tissue.

[0135] Similarly, the cannula 104 illustrated in FIGS. 8A and 8Bincludes a wall 106 having an inner portion 108 defining a fluid volume110. Upon the introduction of fluid under pressure through a supplypassage 112 in the wall 106, the wall portion 108 expands radiallyinwardly to close at least partially the central opening 113 in thecannula 104. The expanding portion 114 of the cannula 104 thus acts as avalve or seal for the central opening 110 of the cannula. This can bevery useful if it is desired to close the central opening 110 whileleaving the cannula 104 in place in the body tissue. The central passage113 can also be closed completely. Alternatively, the wall portion 108can clamp onto an instrument or scope extending through the passage 113to lock it in place.

[0136] In addition to the cannula inner seals or valves formed by theradially inwardly expanding bladder walls, the present inventioncontemplates cannula inner seals formed by other structures. Forexample, a simple mechanical seal can be used such as a diaphragm seallike the seals 44 and 46 (FIGS. 1-3). Other forms of mechanical sealscan be used, such as a membrane (iris) valve, screw lock, twist lock, orluer lock. It is intended that these alternatives be included within thescope of the invention.

[0137]FIGS. 9A and 9B illustrate a cannula 116 having an expandingportion 118 in its wall 120. Upon the introduction of fluid underpressure through a fluid supply passage 122 in the wall 120, a portion124 of the cannula wall 120 expands radially outwardly while alongitudinally co-extensive portion 126 of the wall 120 expands radiallyinwardly to partially or completely close a central longitudinallyextending passage 128. Thus, the cannula 116 has a portion 118 whichexpands both inwardly and outwardly. The cannulas of FIGS. 7-9 thusillustrate the principle of expanding either inward or outward or bothat selected axial locations along the longitudinal extent of a cannula.

[0138] FIGS. 10A-10C illustrate the expansion of a stretchable cannulaby an expandable member inserted therein. A cannula 130 has a wall 132defining a central longitudinally extending passage 134. The cannula 130is made of a stretchable material having viscoelastic properties wherebythe wall 130 when stretched outwardly will retain its stretchedcondition for a period of time. An expander 136 includes a stalk 138 onthe end of which is mounted an expanding portion 140. Upon insertion ofthe expander 136 into the cannula 130 as illustrated in FIG. 10B, theexpanding portion 140 may be expanded radially outwardly by theintroduction of fluid under pressure through the stalk 138, to stretch awall portion 142 of the cannula wall 132 radially outwardly. Uponsubsequent deflation of the expanding portion 140 of the expander 136,and removal of the expander 136 from the cannula 130, the cannula wallportion 142 remains in its stretched condition for at least a period oftime. The cannula 130 is thereby retained in place in the surroundingtissues while instruments or a scope can be passed through it.

[0139] The present invention contemplates monitoring the pressureapplied to tissue by the expanding cannula. This can be done, forexample, with any known pressure sensor or strain gauge. Such isindicated schematically at 144 in FIG. 10C as being on the wall of thedevice 136 used to stretch the cannula 130. Alternatively, it isindicated schematically at 146 in FIG. 10C as being on the wall of thecannula 130.

[0140] FIGS. 11-13 illustrate a cannula 150 which comprises a cylinderexpandable along its entire length. The cannula 150 has a centrallongitudinally extending working passage 152 defined by an inner wall154. An inflation space 156 separates the inner wall 154 from an outerwall 158 of the cannula 150. A series of tethering cords 160 extendbetween the inner wall 154 and the outer wall 158.

[0141] The inner and outer walls 154 and 158, respectively, of thecannula 150 are constructed so that, upon the introduction of fluidunder pressure into the inflation space 156, both walls expand radiallyoutwardly to a larger diameter. Fluid is introduced through a fluidinflow means (not shown) which may be a simple tube or valve in fluidcommunication with the inflation space 156. The cannula 150 expands fromthe condition shown in FIG. 12 to a further expanded condition asillustrated in FIG. 13. The tethering cords 160 limit movement of theouter wall 158 of the cannula 150 from the inner wall 154 of the cannula150. In a preferred embodiment, the tethering cords 160 comprise fibers(either solid or stranded) having their ends fixed to the inner wall 154and the outer wall 158 and extending therebetween. The tethering cords160 may be unextensible, or they may be somewhat extensible upon theapplication of a relatively large amount of force. Use of the tetheringcords 160 is advantageous in that it allows for controlled expansion ofspaced portions of an inflatable device.

[0142] The cannula 150 is circular in cross sectional shape. It shouldbe understood that the present invention is not limited to circularcannulas, but specifically contemplates the provision of cannulas of anytype described herein of other cross sectional-shapes. The crosssectional shape of a particular cannula may be selected in accordancewith a particular application for that cannula. For example, anelliptical or oval-shaped cannula 162 (FIG. 14) may be more suitable forinsertion between adjacent tissue planes, as it conforms more to theopening between the tissue points. The oval-shaped cannula 162 includesan outer wall 164, an inflation space 166, an inner wall 168, and aworking passage 170 extending axially therethrough. Optionally aplurality of tethering cords 172 extend between the inner wall 168 andthe outer wall 164, and limit movement of the outer wall 164 from theinner wall 168.

[0143]FIG. 15 illustrates, as exemplary of the other shapes of cannulaswhich may be provided, a rectangular (in this case square) shapedcannula 174 optionally having a plurality of tethering cords 176extending between the outer cannula wall 178 and an inner cannula wall180. The inner wall 180 defines a working passage 182 extendinglongitudinally through the cannula 174.

[0144]FIG. 16 illustrates schematically a retractor 510 in accordancewith the present invention. The retractor 510 includes a fluid supplystructure 512 and an expandable balloon or bladder 514 having a flexiblewall located at or near the end of the structure 512. The bladder isexpandable, under the force of fluid under pressure, from an unexpandedor retracted condition as indicated in full lines at 514 to an expandedor extended condition as shown in broken lines at 516. In the expandedcondition, the transverse dimension 518 of the bladder 514 issignificantly greater than its transverse dimension before expansion,that is, the dimension 520. Also, in the expanded condition, thetransverse dimension 518 of the bladder 514 is significantly greaterthan its longitudinal dimension 520.

[0145] When the bladder of the retractor is expanded inside the body, itretracts tissue. As seen in FIG. 17, a bladder 522 is mounted on the endof a separate shaft 524 within a cannula or scope 526. The cannula orscope 526 has been inserted into the body through an opening 528 in theskin (either pre-existing or made in situ) which has a transversedimension 530. The bladder 522 when in its unexpanded condition as shownin broken line is smaller than the dimension 530 of the body opening,but when expanded, it expands to a dimension 532 which is significantlygreater than the dimension 530. An actual space or working space 534 isformed which was not present before the expansion of the bladder.

[0146] The newly-formed working space may be used, for example, forbetter use of a fiber optic scope as illustrated in FIG. 3. In FIG. 18,a retractor 510 is passed through an opening 536 in a cannula 538. Afiber optic scope shown schematically at 540 is also passed through thecannula 538. The cannula 538 is inserted into the body through anopening in the body tissues 542 which is only as large as the outerdiameter of the cannula 538. The retractor 510 is then inflated, withair or another fluid being supplied through a rigid or flexible shaft544 to an expandable bladder 546. The bladder 546 expands transversely,retracting the tissues 542 transversely and creating a working space534. By axial manipulation of the shaft 544, the bladder 546 is movableeither toward the end of the scope 540 in the direction as indicated bythe arrow 548, or away from the end of the scope 540 as indicated by thearrow 550, as desired. Such manipulation of the retractor canselectively move and place the adjoining body tissues where the surgeonwants them to enable better use of the scope 540 by the surgeon.

[0147] As shown in FIG. 19, the retractor 510 may be inserted into acannula 552 through a separate opening 554 therein. The opening 554 isshown on the side of the cannula 552, although, of course, it may be onthe end of the cannula as is typical. Alternatively, the retractor 510may be inserted into the body through an opening in the body tissuesseparate from the opening through which the fiber optic scope isinserted. Either of these options allows for greater flexibility in theinsertion and positioning of the retractor 510 relative to the otherinstruments being used such as the arthroscope.

[0148] Also as indicated in FIG. 19, the bladder 558 may be eccentric oreccentrically located relative to the opening 560 at the junctionbetween the bladder 558 and the shaft 562. This is accomplished by usingknown techniques to form the bladder 558 of a material, construction,and shape such that it expands into the eccentric shape as illustratedin FIG. 19 when inflated by fluid under pressure through the shaft 562.In this manner, an improved visualization and working space 534 iscreated which is eccentrically located relative to the other instrumentsbeing used. This may be preferable when the surgeon is using an angledscope.

[0149]FIG. 19 is illustrative of the fact that the bladder of theretractor of the present invention may be formed so as to expand intoany particular shape as desired for the particular application. Thisfeature is also shown schematically in FIGS. 20A through 20E whichillustrate, respectively, retractor bladders which assume in theirexpanded states in round, oval, eccentric, oblong, and conical shapes.Such shapes may generally be called “nonuniform” shapes for purposes ofthe present invention, and refractors with such a shape will expand in a“non-uniform” manner. Such shapes may include, for example, wedge- orU-shaped filaments which collapse at the skin, then expand at deeptissue planes for visualization and working space. The bladder may alsocup and protect vital tissues such as nerves and arteries while workingon other tissues such as muscle.

[0150] Another typical form of construction is illustrated in FIG. 21,which shows a bladder 564 which in its expanded condition assumes atoroidal shape. Again, the width 566 of the bladder 564 is significantlygreater than its length 568. The bladder 568 is expanded by fluid underpressure received through a fluid channel 570 formed between a cannulaor scope outer wall 572 and inner wall 573. By virtue of the toroidalshape of the bladder 568, the leading end 574 of the scope 576 may bepassed axially completely through the retractor into the working space534 which has been created in the tissues 578. Such a bladder 564 mayalso be mounted on a separate shaft inserted through the scope of thecannula.

[0151] In all cases, the fluid pressure within the bladder of theretractor is monitored and controlled to keep the force exerted by theretractor at a safe level for tissue to prevent tissue necrosis. Asindicated schematically in FIG. 22, a retractor 510 is supplied withfluid under pressure from a fluid pressure source 580 via a fluid supplyline 582. A regulator 584 controls the supply of fluid to the retractor510. A pressure sensor 586 is located within the retractor 510 andsenses the pressure of the fluid within the retractor 510. The pressuresensor 586 sends a signal which is representative of the fluid pressurewithin the retractor 510, via wiring 588, to a monitor 590. The monitor590 is connected via control wiring 592 to the pressure regulator 584.The pressure of the fluid within the retractor 510 may thus be monitoredand controlled either manually or automatically, by means which are wellknown in the art and so need not be described further herein. The source580 of fluid supply may be, for example, the air pressure supply whichis commonly found in hospital operating rooms.

[0152] By virtue of this ability to monitor the pressure within theretractor 510, the retractor 510 can also be a useful diagnostic tool.The strength or pressure or resistance of tissue to movement can bemeasured by the pressure required to move it.

[0153]FIGS. 23 and 24 illustrate the use of a retractor of the presentinvention to stabilize a fiber optic scope. The retractor 510 (FIG. 23)includes a bladder 594 which retracts the body tissues 596 away from thescope 598.

[0154] Since the bladder 594 engages and pushes radially outwardly onbody tissues 596 all around the scope 598, the retractor becomes fixedin position when it is so expanded. If the bladder 594 is fixed to theend of the scope 598, the retractor 510 thereby fixes the end of thescope 598 in position relative to the body tissues 596. When a camera isbeing used with the scope 598, the picture normally moves or jumpsaround because of the movability of the end of the scope 598. This isprevented by so using the retractor 510 to stabilize the scope 598,leaving the surgeon with both hands free to work and a steady view ofthe work area.

[0155]FIGS. 23 and 24 also illustrate how the retractor of the presentinvention can be used to control the placement of the tip of a fiberoptic scope. The retractor 510 is formed with an eccentric bladder 594which retracts the body tissues 596 away from the scope 598 to a greaterdistance in one direction than in another. Thus, by rotating theretractor 510, the surgeon can place the tip of the scope 596 closer tothe body tissue 599 (FIG. 23) on one side of the working space 534, orto the body tissue 597 (FIG. 24) on the other side of the working space534. Such variable placement can, of course, also be attained via use ofa retractor 510 which includes a bladder which can be expanded tovarying shapes.

[0156] The retractor of the present invention has many uses in thesurgical field. The retractor 510 can be used to retract soft tissuefrom bone, for example within a joint. The retractor 510 is insertedbetween the bone and the soft tissue 112. The bladder 594 is thenexpanded. The soft tissue is forced away from the bone. The surgeon maythen use a fiber optic scope or other instrument to work within theworking space created by the retractor 510. The retractor of the presentinvention can provide the force needed to move the soft tissue away fromthe bone may vary between about 100 and 1000 mm Hg, and thus, it isimportant to maintain the proper pressure between the two. The retractor510 can do this since it operates on high fluid pressures of about 10 to1000 mm Hg and it utilizes a high strength material such as Kevlar,Mylar, or another durable polymer such as Polylite®, a product ofReichhold Chemicals, Inc. This simple retraction of soft tissue frombone would otherwise be impossible.

[0157]FIG. 25 illustrates the use of a tethering cord to position abladder portion relative to a cannula wall. A cannula 190 has a mainsection with an outer wall 192 and an inner wall 194 spaced therefrom.The wall 194 divides the interior of the cannula 190 into a workingpassage 196 and an inflation fluid passage 198. The passage 198 opensinto a bladder or flexible wall 200 fixed at the distal end 202 of thecannula 190. Tethering cords 204 extend between the cannula wall 192 anda junction or crown 206 of the bladder or flexible wall 200. Thetethering cords 204 limit movement of the crown portion 206 of thebladder or flexible wall 200 from the cannula wall 192.

[0158] The cannula 190 of FIG. 25 is only illustrative of the many waysin which bladder portions can be positioned relative to cannula portionsby tethering cords such as the tethering cord 204. The number andpositioning and length of the tethering cords determines the relativemovement of the various bladder portions to which they are attached,thus aiding in controlling the expanded shape of the bladder relative tothe cannula.

[0159] The cannula 190 can be used to create an open space in acontinuous mass of body tissue. Thus, a continuous mass 207 (FIG. 26) ofbody tissue is free of naturally occurring openings. The mass 207 ofbody tissue is enclosed by skin 208. The skin 208, like the mass 207 ofbody tissue, is free of naturally occurring openings.

[0160] A small slit or incision 209 (FIG. 27) is formed by a surgeon inthe skin 208. The cannula 190 is then inserted through the slit 209 inthe skin 208. At this time, the bladder 200 in a retracted condition inwhich it is tightly disposed against the outer wall or main section 192of the cannula.

[0161] Once the cannula 190 has been inserted through the slit 209 andmoved into the mass 207 of body tissue, the bladder or flexible wall 200is moved from the retracted condition to an extended condition. This isaccomplished by a conducting fluid pressure through the passage 198 intothe flexible wall 200. The fluid pressure expands the flexible wall 200from a contracted condition to an extended condition.

[0162] As the flexible wall 200 is extended, a portion 211 of the mass207 of body tissue is moved outward away from the outer wall 192 of themain section of the cannula 190. Thus, as the flexible wall 200 isinflated, an outer side surface of the flexible wall presses against theportion 211 of the mass 207 of body tissue, in the manner indicatedschematically by arrows in FIG. 27. This pressure moves at least part ofthe portion 211 of the mass 207 of body tissue toward the left (asviewed in FIG. 27). As this occurs, force is transmitted from theportion 211 of the mass of body tissue to a portion 213 (FIG. 27) of themass 207 of body tissue.

[0163] The force transmitted through the mass 207 of body tissue to theportion 213 of the body tissue moves the portion 213 of the body tissueaway from the distal or axially outer end 202 of the cannula 190. Asthis occurs, an open space 215 is formed at a location in the mass 207of body tissue where there was no space prior to insertion of thecannula 190 and expansion of the flexible wall 200.

[0164] The portion 213 of the mass 207 of body tissue is moved away fromthe distal end 202 of the cannula 190 under the influence of force whichis transmitted through the mass of body tissue from the portion 211 ofthe body tissue to the portion 213 of the mass of body tissue. Thus, theouter side surface of the flexible wall 200 is effective to apply force,in the manner indicated by arrows in FIG. 27, against only the portion211 of the mass 207 of body tissue. Force is transmitted by body tissuefrom the portion 211 of the mass of body tissue to the portion 213 ofthe mass 207 of body tissue. The force transmitted through the bodytissue moves the portion 213 of the mass 207 of body tissue away fromthe distal end 202 of the cannula 190 and thereby create the open space215 in the mass 207 of body tissue.

[0165] Creation of the open space 215 in the mass of body tissueprovides a viewing area adjacent to the distal end 202 of the cannula190 for a surgeon to operate. Thus, a endoscope 217 and an operatingtool 219 can be inserted through the passage 196 in the cannula 190. Theouter or distal ends of the endoscope 217 and operating tool 219 projectbeyond the distal end 202 of the cannula 190 into the open space 215.This enables a surgeon to view the distal end of the operating tool 219through the endoscope 217 and to view the portion of the mass 207 ofbody tissue which is to be operated on with the tool 219. Of course,since the surgeon can view the operations being performed by the tool219, the work of the surgeon on the body tissue 207 is greatlyfacilitated.

[0166] The flexible wall or bladder 200 of the cannula 190 (FIG. 28)includes a side wall 191 and an end wall 193 which are formed of anelastomeric material. When the cannula 190 is inserted through theincision 209, the natural resilience of the elastic end wall 193 andelastic side wall 191 causes the bladder or flexible wall 200 to tightlyenclose the outer wall 192 of the cannula 190. This results in thetethers 204 being enclosed by the bladder or flexible wall 200 and beingpressed against the outer wall 192 of the cannula 190.

[0167] After the cannula 190 has been inserted through the incision 209and moved into the continuous mass 207 of body tissue, the bladder 200is inflated to cause the elastic side wall 191 and end wall 193 of thebladder 200 to move outward to the extended condition shown in FIG. 28.A radially and axially inner end 195 of the side wall 191 of the bladder200 is bonded to the outer side surface of the outer wall 192 of thecannula 190. A radially inner end of the end wall 193 is bonded at 197to the outer side surface of the outer wall 192 of the cannula 190. Anopening for the fluid passage 198 extends through the outer wall 192 ata location between the connection 195 of the side wall 191 with theouter wall 192 of the cannula 190 and the connection 197 of the end wall193 with the outer wall 192 of the cannula.

[0168] When the bladder or flexible wall 200 (FIG. 28) is to be inflatedfrom the retracted condition to the extended condition shown in FIG. 28,fluid pressure is conducted through the passage 198 into the bladder200. As the fluid pressure flows into the bladder 200, an annularchamber 199 is established around the outer wall 192 of the cannula 190.As this occurs, the side wall 191 of the bladder 200 presses body tissueradially outward and axially away from the distal end 202 of the cannula190 in the manner indicated by the arrows in FIG. 27. As this isoccurring, the body tissue extends axially outward from the junction 206between the side wall 191 and end wall 193 of the bladder or flexiblewall 200. The body tissue which extends outward from the junction orcrown 206 of the bladder 200 is tensioned and tends to continue outwardfrom the junction. Due to the fact that the end wall 193 extendsradially outward from the cylindrical outer wall 192 of the cannula 190,an opening is formed immediately axially outward from the end wall 193as the bladder 200 is inflated.

[0169] As the bladder 200 is inflated, the tether cords 204 are extendedfrom a nonlinear configuration toward the linear configurationillustrated in FIG. 28. When the bladder or flexible wall 200 reachesthe fully inflated condition shown in FIG. 28, an inflated structure isformed. The tether cords 204 restrain the junction between the side wall191 and 193 from moving further radially outward. This results in theelastic side wall 191 having a configuration corresponding to theconfiguration of a portion of a cone and the elastic end wall 193 havinga configuration corresponding to the configuration of a flat annulardisk. The side wall 191 and end wall 193 are initially formed to thisconfiguration while they are in a stretched condition over a formingtool. The tethering cords 204 cooperate with the side wall 191 and endwall 193 to ensure that the inflated structure formed by the bladder 200has the configuration illustrated in FIG. 28.

[0170] The body tissue 207 which is pressed radially outwardly andaxially away from the distal end 202 of the cannula 190 by movement ofthe bladder 200 from the retracted condition to the expanded conditionshown in FIG. 28 causes the body tissue to move away from the end wall193 as the bladder is inflated. This results in the formation of theopen space 215 axially outwardly from the end wall 193. Thus, theportion 211 of the body tissue disposed to the left (as viewed in FIG.28) of the inflated bladder or flexible wall 200 pulls or tensions theportion of the body tissue which extends across the circular crownportion or junction 206. The forces transmitted through the body tissueitself tends to pull the body tissue away from the end wall 193 to formthe open space 215 in the manner illustrated in FIG. 28.

[0171] A cannula 600 (FIGS. 29 and 30) has the same general constructionas the cannula 190 of FIGS. 25-28. The cannula 600 includes a tubularmain section 601 having a cylindrical outer wall 602 which extends froma proximal end portion (not shown) of the cannula 600 to a distal endportion 604 of the cannula. A flexible wall or bladder 606 is connectedwith the wall 602 of the main section 601.

[0172] The flexible wall 606 has a proximal end portion 607 which isbonded to an annular shoulder 608 formed in the wall 602. A cylindricalclamp ring 609 also secures the proximal end portion 607 to the wall 602of the main section 601 of the cannula 600.

[0173] A distal end portion 610 of the flexible wall 606 is connected tothe distal end of the main section 601 of the, cannula 600. In theillustrated embodiment of the invention, the distal end portion 610 ofthe flexible wall is bonded to the distal end of the main section 601 ofthe cannula 600. However, the distal end portion 610 of the flexiblewall 606 could be connected to the distal end of the-main section 601 inother ways such as by the use of a mechanical retainer. When theflexible wall 606 is in the initial or retracted condition shown in FIG.29, the flexible wall tightly adheres to the main section 601 of thecannula 600 to provide a smooth outer surface which has a minimum ofinterference with body tissue as the cannula 600 is inserted into acontinuous mass of body tissue.

[0174] An inner wall 612 cooperates with the wall 602 to form a passage614 for fluid. The passage 614 has a proximal end (not shown) at whichfluid under pressure is conducted into the passage. The passage 614 hasa plurality of circular distal openings 616 through which fluid can flowfrom the passage 614 to a space enclosed by the flexible wall 606.

[0175] When the flexible wall 606 is to be inflated, fluid pressureflows through the passage 614 and opening 616 and is applied against aninner side surface 617 (FIG. 29) of the flexible wall. The fluidpressure applied against the inner side surface 617 of the flexible wall606 causes the flexible wall to move from the retracted condition shownin FIG. 29 toward the fully extended condition shown in FIG. 30. As thisoccurs, a plurality of tether cords 618 are pulled from a nonlinear orcoiled configuration toward the linear configuration shown in FIGS. 30and 31.

[0176] When the flexible wall 606 is in the retracted condition shown inFIG. 29, the flexible wall covers the tethers 618 and presses themfirmly against the tubular wall 602 of the main section 601 of thecannula 600. Since the tethers 618 are enclosed by the flexible wall606, they do not interfere with insertion of the cannula 600 into acontinuous mass of body tissue 207 where an opening does not naturallyoccur. The relatively high pressure fluid conducted from the passage 614through the openings 616 move the flexible wall 606 outwardly away fromthe main section 601 of the cannula 600 to initiate the formation of aninflation fluid chamber 620. As this occurs, the flexible wall 606 formsan inflated structure 622.

[0177] The inflated structure 622 has a side wall 624 and an end wall626. The side wall 624 and end wall 626 are connected at a circularjunction 628. The side wall 624 has a configuration corresponding to theconfiguration of a portion of a cone while the end wall 626 has aconfiguration corresponding to the configuration of a flat annular diskwhen the flexible wall 606 is in the fully extended position of FIG. 30.The tethering cords 618 limit outward movement of the junction 628between the side wall 624 and the end wall 626 to impart the desiredconfiguration to the inflated structure 622.

[0178] Each of the tethering cords 618 has an outer end portion which issecured to the inner side surface 617 of the flexible wall 606 at thejunction 628. In the illustrated embodiment of the invention, thetethering cords 618 are bonded to the elastomeric material forming theflexible wall 606. However, it is contemplated that the tethering cords618 could be connected with the flexible wall 606 in many differentways. The inner end portions of the tethers 618 are bonded to the mainsection 601 of the cannula 600. The inner end portions of the tethers618 could be secured to the main section 601 of the cannula 600 in manydifferent ways other than bonding.

[0179] The tethering cords 618 limit radially outward movement of thejunction 628 between the end wall 626 and side wall 624. By limitingoutward radial movement of the end wall 626 and the side wall 624, thetethering cords 618 restrain the elastic material of the flexible wall606. This results in the inflated structure 622 having a configurationwhich corresponds to the configuration of a portion of a cone.

[0180] Once the flexible wall 606 has been moved to the extendedcondition of FIG. 30, instruments, such as an endoscope and/or operatingtools, can be inserted through a cylindrical central opening 630 (FIG.31) formed in the main section 601 (FIGS. 29 and 30) of the cannula 600.In addition to the tethers 618, reinforcing fibers 632 (FIGS. 32, 33 and34) are utilized to impart the desired configuration to the inflatedstructure 622.

[0181] A portion of the reinforcing fibers 632 is disposed in the sidewall 624 (FIGS. 32 and 33) of the inflated structure 622. Anotherportion of the reinforcing fibers 632 is disposed in the end wall 626 ofthe inflated structure 622. The reinforcing fibers 632 cooperate withthe elastomeric material, which may be silicone, or latex, to restrainthe elastomeric material of the flexible wall 606 against excessivestretching under the influence of fluid pressure applied against theinner side surface 617 (FIGS. 30 and 31) of the flexible wall 606.

[0182] In the illustrated embodiment of the invention, the inflatedstructure 622 has a configuration corresponding to the configuration ofa portion of a cone. Therefore, a proximal portion 607 of the side wall604 has a smaller diameter than a distal end portion 633 of the sidewall 624. The density of reinforcing fibers 632 in the proximal endportion 607 (FIG. 32) of the side wall 624 is greater than the densityof reinforcing fibers 632 in the distal portion 633 of the side wall624. By having the reinforcing fibers in the proximal end portion 607(FIG. 32) of the side wall 624 closer together, the reinforcing fibersare effective to limit outward radial expansion of the proximal portion607 of the side wall 624. The relatively widely spaced reinforcingfibers 632 (FIG. 23) in the distal end portion 633 of the side wall 624allow the distal end portion 633 of the side wall 624 to expand radiallyoutwardly to a greater extent than the proximal end portion 607 of theside wall 624.

[0183] The reinforcing fibers 632 in the proximal end portion 607 of theside wall 624 (FIG. 32) include fibers 634 having longitudinal axeswhich extend generally parallel to a longitudinal central axis of themain section 601 of the cannula 600. In addition, reinforcing fibers 635extend circumferentially around the distal portion 607 of the side wall624. The reinforcing fibers 635 have longitudinal axes which extendgenerally perpendicular to the longitudinal axis of the reinforcingfibers 634. The longitudinal extending fibers 634 and thecircumferentially extending fibers 635 reinforce the proximal portion607 of the side wall 624 to limit the extent to which the fluid pressureapplied against the inner side surface 617 of the side wall is effectiveto stretch the elastomeric material of the flexible wall 606.

[0184] Similarly, the distal end portion 633 (FIG. 33) of the side wall624 has longitudinally extending fibers 636 having longitudinal axeswhich extend parallel to the longitudinal central axis of the mainsection 601 of the cannula 600. The reinforcing fibers 632 in the distalend portion 633 of the side wall 624 also include circumferentiallyextending fibers 637 which are perpendicular to the longitudinallyextending fibers 636. The reinforcing fibers 632 in the distal portionof the side wall 624 are far more widely spaced than the reinforcingfibers in the proximal end portion 607 of the side wall 624. Thisenables the elastomeric material of the distal end portion 633 tostretch under the influence of fluid pressure applied against the innerside surface 617 (FIG. 30) of the side wall 624. Therefore, the distalportion 633 of the side wall 624 stretches to have a substantiallygreater diameter than the proximal portion 607 of the side wall 624.

[0185] The reinforcing fibers 632 in the end wall 626 (FIG. 34) includefibers 638 which extend radially outwardly from the cylindrical passage630 through the main section 601 of the cannula. Circumferentiallyextending fibers 639 cooperate with the radially extending fibers 638 tolimit the expansion of the end wall 626 under the influence of fluidpressure applied against the inner side surface 617 of the flexible wall606. During formation of the flexible wall 606, the elastomeric materialof the flexible wall is configured to have a configuration correspondingto the desired, generally conical, configuration of the inflatedstructure 622 (FIG. 30).

[0186] The cannula 600 is inserted into a continuous mass of bodytissue, corresponding to the continuous mass 207 (FIG. 26) of bodytissue, with the flexible wall 606 of the cannula 600 in the retractedcondition illustrated in FIG. 29. This enables the cannula 600 to beinserted through a relatively small incision formed in the skinenclosing the continuous mass of tissue. Prior to insertion of thecannula 600 into the continuous mass of tissue, the continuous mass oftissue is free of any openings. As the cannula 600 is inserted into thecontinuous mass of body tissue with the flexible wall 606 in theretracted condition of FIG. 29, the relatively smooth outer side surfaceof the cannula is effective to press aside the body tissue with aminimum of damage to the tissue.

[0187] Once the cannula 600 has been inserted into the continuous massof body tissue, fluid under pressure is conducted through the passage614 (FIG. 29) to initiate inflation of the flexible wall 606. As thisoccurs, the flexible wall 606 begins to move away from the main section601 of the cannula 600. This results in an outer side surface 640 of theflexible wall 606 pressing against the body tissue to move the bodytissue away from the main section 601 of the cannula 600.

[0188] As the inflation of the flexible wall 606 continues, the outerside surface 640 of the flexible wall disposed on the conical side wall624 presses the tissue both radially outwardly and axially away from thedistal end of the main section 601 of the cannula 600. As this occurs,force is transmitted through the body tissue itself to pull the bodytissue away from the end wall 626 and the distal or axially outer end ofthe cannula 600 to initiate the formation of an open space immediatelyaxially outwardly of the end wall 626.

[0189] As the flexible wall 606 continues to move away from theretracted condition of FIG. 29 toward the fully extended condition ofFIG. 30, the tethers 618 are straightened. When the flexible wall 606reaches the fully extended condition of FIG. 30, the tethers 618 limitoutward movement of the junction 628 between the end wall 626 and sidewall 624. Thus, force is transmitted through the tethers 618 from thejunction 628 to the main section 601 of the cannula 600 to limit outwardmovement of the junction 628. The reinforcing fibers 632 (FIGS. 32, 33and 34), cooperate with the tethers 618 to give the side wall 624 theconical configuration shown in FIG. 30 and the end wall 626 a flatannular disk-shaped configuration.

[0190]FIG. 35 illustrates a cannula 210 which is selectively expandableat one or more selected longitudinal locations. The cannula 210 includesa series of expandable wall segments defining a longitudinally extendingcentral working passage 212. The expandable segments illustrated includea segment 214, a segment 216, a segment 218, and a segment 220. As anexample, the segment 218 is expandable, upon the introduction of fluidunder pressure, to an expanded condition as illustrated at 222 in FIG.35. Thus, in accordance with the principles illustrated in FIG. 35, acannula or other inflatable medical device can be expanded forpositioning or sealing at one or more selected longitudinal locations.

[0191]FIG. 36 similarly illustrates a cannula 224 having a plurality ofexpandable segments 226 through 234 spaced circumferentially around thedistal end portion 236 of the cannula 224. Each of the segments 226-234is selectively expandable, as illustrated-in FIG. 37 showing the segment234 expanded radially outwardly. Accordingly, it is seen that thepresent invention also contemplates a cannula or bladder, or otherinflatable medical device, having a plurality of circumferentiallydisposed segments expandable radially outwardly upon the selectivecontrol of the user of the device. Such selective expansion is useful inselectively positioning the cannula within the tissue in which it islocated, in avoiding damage to certain tissue such as nerve tissue, orin protecting or moving certain tissue selectively.

[0192] FIGS. 38-43 illustrate such longitudinally extending radiallyexpansible segments of a cannula or bladder or other inflatable medicaldevice in accordance with the present invention. Each segment shown isone of a series of similar segments (not shown) spaced circumferentiallyaround or formed as part of the wall of a cannula or other device 250.The expansible segment 240 illustrated in FIGS. 38-43 is formed as abellows or accordion and is expandable to a larger extent at its distalend 244 than at its proximal end 242. If the distal end 244 of theexpansible segment 240 is located adjacent a distal end of a cannula,the cannula will thus be expandable directly at its tip. Thebellows-like construction of the segment 240 provides significantstructural rigidity and can transmit in a controlled manner asignificant amount of force between its radially outer surface 246 andits radially inner surface 248 adjacent-the wall of the cannula 250. Thesegment 240 is inflated by introduction of fluid under pressure in aknown manner into the inflation space 252 (FIG. 41).

[0193] The expandable segment 254 illustrated in FIGS. 42 and 43 has asmooth outer skin 256 supported by a plurality of expandablebellows-shaped hoops 258 spaced longitudinally along the length of thesegment 254. The skin 256 presents a smooth surface to adjoining tissuesupon expansion of the segment 254. The hoops 258 provide structuralrigidity to the segment 254, and control the shape of expansion of theskin 256. It should be understood that other configurations of the hoops258, which support the skin 256 of the segment 254, are contemplated.

[0194]FIGS. 44 and 45 illustrate expandable devices having texturedsurfaces for grip and location control. The retractor 260 illustrated inFIG. 44 includes a stalk portion 262 and a bladder portion 264 attachedthereto. The bladder portion 264 has a pebbled surface 266. Theretractor 268 (FIG. 45) has a stalk portion 270 and a bladder portion272. The bladder 272 has a ribbed surface 274. Other types of texturingor finishing may be provided for an expandable device in accordance withthe present invention. Any suitable surface configuration may be used toincrease the grip provided between the outer surface of the expandabledevice and the tissue which it contacts. It should be noted that thesurface texturing may also increase the structural rigidity of theexpanded device.

[0195] FIGS. 46-49 illustrate an expanding device 280 which is preshapedand has a varying wall thickness in its expanding bladder portion. Theexpanding device 280 includes a support member 282 which may be a solidstalk or a hollow cannula or other member. The support member 282 has awidened proximal portion 286, a narrower diameter central portion 288,and a widened distal portion 290.

[0196] Bonded to the support member 282 is an expanding bladder 292. Theexpanding bladder 292 includes a proximal portion 294 bonded to theproximal portion 286 of the support member 282. The expanding bladder292 also includes a distal portion 296 bonded to the distal end portion290 of the support member 282. Extending distally from the portion 294is a first expanding portion 298 having a thinner wall section at itsproximal end 300 and a thicker wall section at its distal end 302.Extending distally from the expanding portion 298 to the thin wallportion 296 is a second expanding portion 304. The second expandingportion 304 is thicker at its proximal end 366, than at its distal end308, having a tapering cross section between the first expanding portion298 and the distal end portion 296.

[0197] When in the unexpanded condition, the first and second expandingportions 298 and 304, respectively, of the expandable bladder 292generally lie flat within the recess formed by the narrow portion 288 ofthe support member 282. Upon the introduction of fluid under pressureinto the interior of the bladder 292 through a port (not shown) in thesupport member 282, the bladder 292 expands from the conditionillustrated in FIG. 46 to the-condition illustrated in FIG. 47. Theexpanding portions 298 and 304 expand radially outwardly as illustrated.Because the material of the bladder 292 is thinner at its axially outerend portions 300 and 308, that material stretches more and so thethicker portions 302 and 306 move radially outwardly the greatestamount. The proximal and distal end portions 294 and 296, respectively,are prestretched, that is, stretched to a diameter greater than theirrelaxed condition, for insertion over the support member 282.

[0198] Thus, it is seen that the wall thickness of a bladder can bevaried at selected locations to control the rates and distances ofexpansion of the bladder portions. Further, portions of the bladder canbe prestretched so that they reach their maximum elongation at anearlier amount of expansion. These factors can be used to control theexpanded shape of the bladder.

[0199] In addition, there may be provided ribs such as thelongitudinally extending ribs 310 illustrated in FIGS. 48 and 49 whichare of an increased wall thickness to provide structural support andexpansion control of the elastomeric material of the bladder. The ribs310 are illustrative of any region of increased wall thickness used tocontrol the shape of expansion. Such regions may run longitudinally asillustrated in the device 280, or may run transversely orcircumferentially or in other directions. Taken in combination, all ofthese factors are usable to control the shape of expansion of aninflatable medical device.

[0200] In accordance with a further embodiment of the invention,relatively rigid members such as plates may be molded into relativelyflexible bladder portions to define edges and surfaces, as illustratedin FIGS. 50-52. A medical device 312 (FIG. 50) includes a support member314 such as a cannula to which is attached an expanding (elastomeric)bladder 316. The attachment between the bladder 316 and the supportmember 314 is not shown in these particular cross-sectional views, butmay be in any manner known or as described herein. The bladder 316 hasan elastomeric curved portion 318 and an elastomeric portion 319. Aplate 320 is molded into the bladder 316 and has an edge 322. A secondplate 324 molded into the bladder 316 has an edge 326. Upon theintroduction of fluid under pressure into the volume between the supportmember 314 and the bladder 316, the bladder expands radially outwardlyfrom the condition shown in FIG. 50 to the condition shown in FIG. 51.Although the elastomeric portion 318 of the bladder 316 changesdimensions, the plates 320 and 324 do not. Thus, the expanding device316 includes flat surfaces and edge surfaces which move radiallyoutwardly and maintain their rigid condition upon expansion of thedevice 312. The plates 320 and 324 thus control and partially define theexpanded shape of the device 312.

[0201] Alternatively or additionally, as illustrated in FIG. 52,tethering cords 328 may be employed between the support member 314 andthe plates 320 and 324. The tethering cords 328 also serve to controland/or limit expansion of the device 312. Additionally, it can be seenthat the device of FIG. 52 includes elastomeric bladder portions 330extending directly between the plates 320 and 324 and the support member314. Again, this is an alternative form of the construction. Expandingbladders constructed in accordance with the present invention can useany one or more of these various means of controlling or limiting theexpansion of the inflatable medical device, in order to achieve theoptimum structure for the particular application.

[0202]FIGS. 53 and 54 further illustrate the use of rigid plates ormembers molded into elastomeric material of an inflatable medicaldevice. An expanding bladder 332 is fixed circumferentially by means notshown around a cannula 334. The cannula 334 includes a cannula wall 336defining a longitudinally extending central opening 338. The expandingbladder 332 includes an elastomeric material 340 within which are moldeda series of relatively rigid plates 342. Between the expanding bladder332 and the cannula wall 336 is a fluid inflation space 344. Upon theintroduction of fluid under pressure into the inflation volume 344, theexpanding bladder 332 expands radially outwardly from the conditionshown in FIG. 53 to the condition shown in FIG. 54. The elastomericmaterial 340 stretches and elongates circumferentially. The areas of theelastomeric material 340 which are devoid of plates 342 stretch further,thus allowing the plates 342 to separate. The plates 342, which werepreviously in overlapping position, are separated as illustrated in FIG.54. The plates 342 impart structural rigidity and strength to theelastomeric material 340. The invention is not limited to the particularconfiguration of rigid plates and elastomeric material illustrated, butcontemplates any such configuration of relatively rigid members orportions in a relatively stretchable matrix material.

[0203] The expanding device illustrated in FIGS. 55 and 56 includes adoubled-over bladder portion to allow maximum expansion at the distalend portion of the device. The device includes a cannula or stalk orother support member 350. An expanding bladder 352 is bonded at 354 to aproximal portion 356 of the support member 350, and at 358 to a distalend portion 360 of the support member 350. The material of the expandingbladder 352 is doubled-over at 362 adjacent the distal end portion 360.Upon the introduction of fluid under pressure into the volume defined bythe bladder 352, through a fluid supply port 364, the bladder 352expands from the condition shown in FIG. 55 to the condition shown inFIG. 56. Because of the doubled-over portion 362 of the bladder 352,maximum expansion is gained at the distal end of the device rather thanat the center or the proximal end of the expanding bladder 352. Again,such a device may include bladder portions having varying wallthicknesses as discussed above, tethering cords, etc., all to controlthe expanded shape of the device.

[0204] The expanding device illustrated in FIGS. 57 through 62 includesa doubled-over bladder portion to allow maximum expansion at the distalend portion of the device in the manner previously described inconnection with FIGS. 55 and 56. The device includes a cannula having amain section or stalk 850. An expanding bladder or flexible wall 852 isbonded at 854 to a proximal end portion 856 of the support member 850and at 858 to a distal end portion 860 of the main section 850 (FIGS. 57and 58). The material of the expanding bladder 852 is doubled-over at862 adjacent to the distal end portion 860.

[0205] Upon introduction of fluid under pressure into the volume-definedby the bladder 852, through a fluid supply port 864 (FIG. 57), thebladder or flexible wall 852 expands from the condition shown in FIG. 57to the condition shown in FIG. 58. Because of the doubled-over portion862 of the bladder 852, maximum expansion is gained at the distal end ofthe device rather than at the center or proximal end of the expandingbladder 852. Again, such a device may include bladder portions havingvarying wall thicknesses as discussed above or reinforcing fibers tocontrol the expanded shape of the device.

[0206] In the embodiment illustrated in FIGS. 57 and 58, tethering cords870 extend from the main section 850 of the cannula to a junction 872between a side wall 874 and an end wall 876 (FIG. 58) of the flexiblewall or bladder 852. The tethering cords 870 limit the extent of outwardmovement of the junction 872 when the flexible wall or bladder 852 isinflated from the retracted condition of FIG. 57 to the extendedcondition of FIG. 58. The side wall 874 of the inflated flexible wallhas a configuration corresponding to the configuration of a portion of acone. The end wall 876 has a configuration corresponding to theconfiguration of an annular disk. However, it should be understood thatthe end wall 876 slopes radially and axially outwardly from a locationwhere the side wall 876 is connected with the main section 850 of thecannula to the junction 872 between the end wall and the side wall 874.

[0207] In accordance with a feature of this embodiment of the invention,tethering cords 870 extend outwardly from the distal end portion of themain section 850 to the junction 872 between the side wall 874 and endwall 876. The tethering cords 870 limit outward movement of the flexiblewall or bladder 852 to assist in imparting the desired configuration tothe bladder when it is in the expanded condition of FIG. 58. Althoughonly a pair of tethering cords 870 are shown in FIGS. 57 and 58, itshould be understood that there is a circular outer array 880 oftethering cords which extend from the main section 850 of the cannulaoutwardly to the junction 872. Although any desired number of tetheringcords could be used, in the illustrated embodiment of the invention,there are nine tethering cords in the circular array 880 of tetheringcords.

[0208] In the embodiment of the invention illustrated in FIGS. 59-62,the cannula, has the same general construction as the cannula of FIGS.57 and 58. However, in the embodiment of the invention illustrated inFIGS. 59-62, tethering cords are provided between an inner side surfaceof the side wall 874 of the bladder or flexible wall and the mainsection 850 of the cannula. Since the embodiment of the inventionillustrated in FIGS. 59-62 is generally similar to the embodiment of theinvention illustrated in FIGS. 57 and 58, similar numerals have beenutilized to designate similar components.

[0209] In accordance with a feature of the embodiment illustrated inFIGS. 59-62, an intermediate array 882 of tethering cords 870 extendsbetween the main section 850 of the cannula and the inner side surfaceof the flexible wall or bladder 852. In addition, an axially inner array884 of tethering cords 870 extends between the inner side surface of thebladder or flexible wall and the main section 850 of the cannula.

[0210] The three arrays 880, 882, and 884 of tethering cords 870 used torestrain outward-movement of the flexible wall or bladder 852 in theembodiment of the invention illustrated in FIGS. 59-62 are effective tocause the extended flexible wall 852 to form an inflated structurehaving a generally conical configuration.

[0211]FIG. 63 illustrates an expanding bladder 370 having adjoiningportions with different material characteristics. The device is shown inend view as disposed circumferentially around a cannula 372. Alternateportions 374 of the device are made of a first material having a firstset of material characteristics, while the interfitted portions 376 aremade of a second material having a second set of materialcharacteristics. For example, one material may have a lower modulus ofelasticity and the other a higher modulus of elasticity. One may bethicker and the other thinner, one may be elastomeric and the other not.Other combinations are possible. The portions may be bonded togetherwith adhesive, may be heat-sealed together, or may be solvent sealed.One portion can be made of metal. PVC is also a suitable material.

[0212] Upon the introduction of fluid under pressure into the expandingdevice 370, the portions 374 and 376 expand or move at different ratesor into different shapes. The adjoining of different materials can beused to control the expanded shape of the device 370.

[0213]FIG. 64 illustrates an expanding device 380 having an expandingbladder 382 made of a plurality of materials laminated together. Theexpanding portion 382 is mounted on a stalk or cannula 384. The bladder382 includes an outer layer 386 of a first material laminated to aninner layer 388 of a second material. Again, the layers may havediffering material characteristics—perhaps polymers with specificproperties bonded together. For example, the layer 386 may be of adifferent durometer from the material of the layer 388. One of thelayers may provide structural support while the other provides fluidsealing capabilities. One layer may provide puncture resistance whilethe other provides expansion shape control. These are some of the manyproperties available with such laminated structures.

[0214] It should also be noted that the expandable bladder 382 has anexpanded dimension many times greater than its unexpanded dimension asillustrated in dashed lines in FIG. 64. This is illustrative of thelarge degree of expansion which the expandable bladders of the presentinvention are able to generate. For example, expandable bladders inaccordance with the present invention have been built having expansionrates of approximately 700% as compared to the unexpanded diameter.

[0215]FIG. 65A illustrates a triangular shaped expanding element 400fixed to a supporting device indicated at 402. The expanding element 400has relatively thin walled portions 404 and a relatively thick wallportion 406. Upon the introduction of fluid under pressure into thevolume 408 defined by the bladder 400, the relatively thin walledportions 404 are stretched to a greater extent than the relatively thickwalled portion 406. In the similar expanding segment 410 (FIG. 65B), afiber 412 is embedded in the elastomeric material of the expandingsegment to control and limit its expansion. Again, in the similarexpanding segment 414 illustrated in FIG. 65C, a fiber mesh 416 isembedded in the elastomeric material of the expanding segment tostrengthen it and to control its expansion.

[0216] The expanding segments illustrated in FIGS. 66A, 66B, and 66C aresimilar to FIGS. 65A-65C in structural composition but are trapezoidalshaped rather than triangular shaped. FIG. 66A illustrates an expandingsegment 418 connected with a support member 420. The segment 418includes relatively thin walled portions 422 and a relatively thickwalled portion 424. Upon the introduction of fluid under pressure intothe volume defined by the expanding portion 418, the relatively thinwalled portions 422 stretch to a greater extent than the relativelythick walled portion 424 whereby the relatively thick walled portion 424moves radially outwardly to a greater extent. The expanding segment 426(FIG. 66B) includes an embedded reinforcing fiber 428 for expansioncontrol purposes. The expanding segment 430 (FIG. 66C) includes anembedded fiber mesh 432 for structural support and expansion controlpurposes. The structural compositions and uses of embedded fibers andfiber meshes illustrated in FIGS. 65 and 66 are merely illustrative ofthe various ways in which fibers embedded in the elastomeric material ofan expanding medical device can be used to control the expansionthereof.

[0217] FIGS. 67A-67C illustrate the use of overlapping and/or incompletereinforcing fibers for expansion control. A stretchable elastomericmaterial 434 (FIG. 67A) has a plurality of fibers or other reinforcingelements 436 embedded therein. As the stretchable material 434 iselongated, the elastomeric material in the stretch zones 438 (FIG. 67C)between the fiber portions 436 stretches to a greater extent than thematerial immediately around the fibers 436. Further, the embedded fibersresist transverse expansion of the elastomeric material whileencouraging longitudinal expansion as shown. These drawings are merelyillustrative of the use of the concept of overlapping fibers withstretch zones to control expansion rates of an elastomeric material usedin an expanding medical device such as a cannula or catheter. Thepresent invention contemplates other such arrangements of fibers orreinforcing elements in the elastomeric materials.

[0218] For example, FIGS. 68-70 illustrates a bladder retractor 440fixed to a cannula 442. A plurality of circumferentially extendingreinforcing fibers 444 are embedded in an elastomeric matrix material446. In addition, a plurality of tethering cords 448 extend radiallybetween the cannula 442 and the elastomeric material 446 to limit theradially outwardly expansion. As can be seen in FIG. 70, the reinforcingfibers 444 are not complete but rather are broken fibers extendingcircumferentially within the matrix material 446 to define stretch tonesbetween them. Alternatively, the reinforcing fibers may be complete, asillustrated in FIGS. 71 and 72. In the retractor 450 illustrated inFIGS. 71 and 72, a plurality of complete circumferentially extendingreinforcing fibers 452 are embedded in the matrix material 454. Theretractor 456 illustrated in FIGS. 73 and 74 includes a plurality oflongitudinally extending incomplete reinforcing fibers 458 embedded inthe matrix material 460. The retractor 462 illustrated in FIGS. 75 and76 includes a plurality of longitudinally extending complete reinforcingfibers 464 embedded in an elastomeric matrix material 466. Again, theinvention contemplates other such configurations of reinforcing fibersembedded in matrix materials, and is not limited to those shown.

[0219] FIGS. 77-79 illustrate a series of expandable bladders laminatedtogether to define a structural unit 470. A series of upperlongitudinally extendable bladders 472 have their ends fixed between anupper member 474 and a central member 476. A series of lowerlongitudinally extending bladders 478 have their ends fixed between thecentral member 476 and a lower member 480. A covering or retainer 482(FIG. 79) may enclose all of the units. Upon the introduction of fluidunder pressure, the bladders 472 and 478 expand longitudinally from thecondition illustrated in FIG. 77 to the condition illustrated in FIG.78. When the bladders 472 and 478 are fully inflated as illustrated inFIG. 54, they define, together with the members 474, 476 and 480 and theretainer 482, a rigid structural unit. This type of laminated bladderconstruction will find many suitable uses. It should be understood thatother configurations of bladders laminated together are contemplated andare within the scope of the invention.

[0220] From the above description of the invention, those skilled in theart will perceive improvements, changes and modifications in theinvention. Such improvements, changes and modifications within the skillof the art are intended to be covered by the appended claims.

I claim:
 1. A balloon dissection device comprising: a support member having a longitudinal axis, a proximal portion, a central portion, a distal portion, and a lumen, wherein the central portion has a smaller diameter than a diameter of the proximal and distal portions; and an inflatable balloon mounted on the support member and having an inner surface, an outer surface, a proximal end, a distal end, and an inflatable portion therebetween, the support member extending at least the entire length of the inflatable balloon when fully inflated such that the inflatable portion expands between the proximal and distal portions of the support member, the inflatable balloon comprised of a thin layer of uniform material wherein the thickness of the material is increased intermittently to form elongate ribs oriented along the inner surface of the balloon, the ribs having a longitudinal axis substantially parallel to the longitudinal axis of the support member. 